In this paper, we use the technique of survival analysis to investigate how long Wikipedia editors remain active in editing. Our results show that although the survival function of occasional editors roughly follows a lognormal distribution, the survival function of customary editors can be better described by a Weibull distribution (with the median lifetime of about 53 days). Furthermore, for customary editors, there are two critical phases (0-2 weeks and 8-20 weeks) when the hazard rate of becoming inactive increases. Finally, customary editors who are more active in editing are likely to keep active in editing for longer time.